From abc2d9039fda5d57ed9bc0ec05b0f6cbc523bd99 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Aug 21 2023 16:19:46 +0000 Subject: [PATCH 1/3] dlm_controld: update rbtree implementation This patch updates the rbtree implementation taken from the Linux kernel. --- diff --git a/README.license b/README.license index ededf66..d53f589 100644 --- a/README.license +++ b/README.license @@ -7,10 +7,13 @@ libdlm/libdlm_internal.h GPLv2 dlm_controld/list.h (copied from linux kernel) +dlm_controld/linux_helpers.h (various GPLv2 functions copied from linux kernel) GPLv2+ dlm_controld/rbtree.c (copied from linux kernel) dlm_controld/rbtree.h (copied from linux kernel) +dlm_controld/rbtree_augmented.h (copied from linux kernel) +dlm_controld/rbtree_types.h (copied from linux kernel) all other original files diff --git a/dlm_controld/linux_helpers.h b/dlm_controld/linux_helpers.h new file mode 100644 index 0000000..5ef1346 --- /dev/null +++ b/dlm_controld/linux_helpers.h @@ -0,0 +1,11 @@ +/* Copied from linux kernel */ + +#ifndef __DLM_LINUX_HELPERS__ +#define __DLM_LINUX_HELPERS__ + +#define WRITE_ONCE(x, val) \ +do { \ + *(volatile typeof(x) *)&(x) = (val); \ +} while (0) + +#endif /* __DLM_LINUX_HELPERS__ */ diff --git a/dlm_controld/list.h b/dlm_controld/list.h index 8100cbc..a2a5e5f 100644 --- a/dlm_controld/list.h +++ b/dlm_controld/list.h @@ -15,7 +15,6 @@ const typeof( ((type *)0)->member ) *__mptr = (ptr); \ (type *)( (char *)__mptr - offsetof(type,member) );}) - /* * These are non-NULL pointers that will result in page faults * under normal circumstances, used to verify that nobody uses diff --git a/dlm_controld/rbtree.c b/dlm_controld/rbtree.c index 9f49917..d07ffc2 100644 --- a/dlm_controld/rbtree.c +++ b/dlm_controld/rbtree.c @@ -1,284 +1,458 @@ +/* Copied from linux/lib/rbtree.c */ /* Red Black Trees (C) 1999 Andrea Arcangeli (C) 2002 David Woodhouse - - This program is free software; you can redistribute it and/or modify - it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 2 of the License, or - (at your option) any later version. + (C) 2012 Michel Lespinasse - This program is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc. linux/lib/rbtree.c */ -#include -#include "rbtree.h" - -static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) -{ - struct rb_node *right = node->rb_right; - struct rb_node *parent = rb_parent(node); +#include "rbtree_augmented.h" - if ((node->rb_right = right->rb_left)) - rb_set_parent(right->rb_left, node); - right->rb_left = node; +/* + * red-black trees properties: https://en.wikipedia.org/wiki/Rbtree + * + * 1) A node is either red or black + * 2) The root is black + * 3) All leaves (NULL) are black + * 4) Both children of every red node are black + * 5) Every simple path from root to leaves contains the same number + * of black nodes. + * + * 4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two + * consecutive red nodes in a path and every red node is therefore followed by + * a black. So if B is the number of black nodes on every simple path (as per + * 5), then the longest possible path due to 4 is 2B. + * + * We shall indicate color with case, where black nodes are uppercase and red + * nodes will be lowercase. Unknown color nodes shall be drawn as red within + * parentheses and have some accompanying text comment. + */ - rb_set_parent(right, parent); +/* + * Notes on lockless lookups: + * + * All stores to the tree structure (rb_left and rb_right) must be done using + * WRITE_ONCE(). And we must not inadvertently cause (temporary) loops in the + * tree structure as seen in program order. + * + * These two requirements will allow lockless iteration of the tree -- not + * correct iteration mind you, tree rotations are not atomic so a lookup might + * miss entire subtrees. + * + * But they do guarantee that any such traversal will only see valid elements + * and that it will indeed complete -- does not get stuck in a loop. + * + * It also guarantees that if the lookup returns an element it is the 'correct' + * one. But not returning an element does _NOT_ mean it's not present. + * + * NOTE: + * + * Stores to __rb_parent_color are not important for simple lookups so those + * are left undone as of now. Nor did I check for loops involving parent + * pointers. + */ - if (parent) - { - if (node == parent->rb_left) - parent->rb_left = right; - else - parent->rb_right = right; - } - else - root->rb_node = right; - rb_set_parent(node, right); +static inline void rb_set_black(struct rb_node *rb) +{ + rb->__rb_parent_color += RB_BLACK; } -static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) +static inline struct rb_node *rb_red_parent(struct rb_node *red) { - struct rb_node *left = node->rb_left; - struct rb_node *parent = rb_parent(node); - - if ((node->rb_left = left->rb_right)) - rb_set_parent(left->rb_right, node); - left->rb_right = node; - - rb_set_parent(left, parent); + return (struct rb_node *)red->__rb_parent_color; +} - if (parent) - { - if (node == parent->rb_right) - parent->rb_right = left; - else - parent->rb_left = left; - } - else - root->rb_node = left; - rb_set_parent(node, left); +/* + * Helper function for rotations: + * - old's parent and color get assigned to new + * - old gets assigned new as a parent and 'color' as a color. + */ +static inline void +__rb_rotate_set_parents(struct rb_node *old, struct rb_node *new, + struct rb_root *root, int color) +{ + struct rb_node *parent = rb_parent(old); + new->__rb_parent_color = old->__rb_parent_color; + rb_set_parent_color(old, new, color); + __rb_change_child(old, new, parent, root); } -void rb_insert_color(struct rb_node *node, struct rb_root *root) +static __always_inline void +__rb_insert(struct rb_node *node, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)) { - struct rb_node *parent, *gparent; - - while ((parent = rb_parent(node)) && rb_is_red(parent)) - { - gparent = rb_parent(parent); - - if (parent == gparent->rb_left) - { - { - register struct rb_node *uncle = gparent->rb_right; - if (uncle && rb_is_red(uncle)) - { - rb_set_black(uncle); - rb_set_black(parent); - rb_set_red(gparent); - node = gparent; - continue; - } + struct rb_node *parent = rb_red_parent(node), *gparent, *tmp; + + while (true) { + /* + * Loop invariant: node is red. + */ + if (!parent) { + /* + * The inserted node is root. Either this is the + * first node, or we recursed at Case 1 below and + * are no longer violating 4). + */ + rb_set_parent_color(node, NULL, RB_BLACK); + break; + } + + /* + * If there is a black parent, we are done. + * Otherwise, take some corrective action as, + * per 4), we don't want a red root or two + * consecutive red nodes. + */ + if(rb_is_black(parent)) + break; + + gparent = rb_red_parent(parent); + + tmp = gparent->rb_right; + if (parent != tmp) { /* parent == gparent->rb_left */ + if (tmp && rb_is_red(tmp)) { + /* + * Case 1 - node's uncle is red (color flips). + * + * G g + * / \ / \ + * p u --> P U + * / / + * n n + * + * However, since g's parent might be red, and + * 4) does not allow this, we need to recurse + * at g. + */ + rb_set_parent_color(tmp, gparent, RB_BLACK); + rb_set_parent_color(parent, gparent, RB_BLACK); + node = gparent; + parent = rb_parent(node); + rb_set_parent_color(node, parent, RB_RED); + continue; } - if (parent->rb_right == node) - { - register struct rb_node *tmp; - __rb_rotate_left(parent, root); - tmp = parent; + tmp = parent->rb_right; + if (node == tmp) { + /* + * Case 2 - node's uncle is black and node is + * the parent's right child (left rotate at parent). + * + * G G + * / \ / \ + * p U --> n U + * \ / + * n p + * + * This still leaves us in violation of 4), the + * continuation into Case 3 will fix that. + */ + tmp = node->rb_left; + WRITE_ONCE(parent->rb_right, tmp); + WRITE_ONCE(node->rb_left, parent); + if (tmp) + rb_set_parent_color(tmp, parent, + RB_BLACK); + rb_set_parent_color(parent, node, RB_RED); + augment_rotate(parent, node); parent = node; - node = tmp; + tmp = node->rb_right; } - rb_set_black(parent); - rb_set_red(gparent); - __rb_rotate_right(gparent, root); + /* + * Case 3 - node's uncle is black and node is + * the parent's left child (right rotate at gparent). + * + * G P + * / \ / \ + * p U --> n g + * / \ + * n U + */ + WRITE_ONCE(gparent->rb_left, tmp); /* == parent->rb_right */ + WRITE_ONCE(parent->rb_right, gparent); + if (tmp) + rb_set_parent_color(tmp, gparent, RB_BLACK); + __rb_rotate_set_parents(gparent, parent, root, RB_RED); + augment_rotate(gparent, parent); + break; } else { - { - register struct rb_node *uncle = gparent->rb_left; - if (uncle && rb_is_red(uncle)) - { - rb_set_black(uncle); - rb_set_black(parent); - rb_set_red(gparent); - node = gparent; - continue; - } + tmp = gparent->rb_left; + if (tmp && rb_is_red(tmp)) { + /* Case 1 - color flips */ + rb_set_parent_color(tmp, gparent, RB_BLACK); + rb_set_parent_color(parent, gparent, RB_BLACK); + node = gparent; + parent = rb_parent(node); + rb_set_parent_color(node, parent, RB_RED); + continue; } - if (parent->rb_left == node) - { - register struct rb_node *tmp; - __rb_rotate_right(parent, root); - tmp = parent; + tmp = parent->rb_left; + if (node == tmp) { + /* Case 2 - right rotate at parent */ + tmp = node->rb_right; + WRITE_ONCE(parent->rb_left, tmp); + WRITE_ONCE(node->rb_right, parent); + if (tmp) + rb_set_parent_color(tmp, parent, + RB_BLACK); + rb_set_parent_color(parent, node, RB_RED); + augment_rotate(parent, node); parent = node; - node = tmp; + tmp = node->rb_left; } - rb_set_black(parent); - rb_set_red(gparent); - __rb_rotate_left(gparent, root); + /* Case 3 - left rotate at gparent */ + WRITE_ONCE(gparent->rb_right, tmp); /* == parent->rb_left */ + WRITE_ONCE(parent->rb_left, gparent); + if (tmp) + rb_set_parent_color(tmp, gparent, RB_BLACK); + __rb_rotate_set_parents(gparent, parent, root, RB_RED); + augment_rotate(gparent, parent); + break; } } - - rb_set_black(root->rb_node); } -static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, - struct rb_root *root) +/* + * Inline version for rb_erase() use - we want to be able to inline + * and eliminate the dummy_rotate callback there + */ +static __always_inline void +____rb_erase_color(struct rb_node *parent, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)) { - struct rb_node *other; - - while ((!node || rb_is_black(node)) && node != root->rb_node) - { - if (parent->rb_left == node) - { - other = parent->rb_right; - if (rb_is_red(other)) - { - rb_set_black(other); - rb_set_red(parent); - __rb_rotate_left(parent, root); - other = parent->rb_right; - } - if ((!other->rb_left || rb_is_black(other->rb_left)) && - (!other->rb_right || rb_is_black(other->rb_right))) - { - rb_set_red(other); - node = parent; - parent = rb_parent(node); + struct rb_node *node = NULL, *sibling, *tmp1, *tmp2; + + while (true) { + /* + * Loop invariants: + * - node is black (or NULL on first iteration) + * - node is not the root (parent is not NULL) + * - All leaf paths going through parent and node have a + * black node count that is 1 lower than other leaf paths. + */ + sibling = parent->rb_right; + if (node != sibling) { /* node == parent->rb_left */ + if (rb_is_red(sibling)) { + /* + * Case 1 - left rotate at parent + * + * P S + * / \ / \ + * N s --> p Sr + * / \ / \ + * Sl Sr N Sl + */ + tmp1 = sibling->rb_left; + WRITE_ONCE(parent->rb_right, tmp1); + WRITE_ONCE(sibling->rb_left, parent); + rb_set_parent_color(tmp1, parent, RB_BLACK); + __rb_rotate_set_parents(parent, sibling, root, + RB_RED); + augment_rotate(parent, sibling); + sibling = tmp1; } - else - { - if (!other->rb_right || rb_is_black(other->rb_right)) - { - rb_set_black(other->rb_left); - rb_set_red(other); - __rb_rotate_right(other, root); - other = parent->rb_right; + tmp1 = sibling->rb_right; + if (!tmp1 || rb_is_black(tmp1)) { + tmp2 = sibling->rb_left; + if (!tmp2 || rb_is_black(tmp2)) { + /* + * Case 2 - sibling color flip + * (p could be either color here) + * + * (p) (p) + * / \ / \ + * N S --> N s + * / \ / \ + * Sl Sr Sl Sr + * + * This leaves us violating 5) which + * can be fixed by flipping p to black + * if it was red, or by recursing at p. + * p is red when coming from Case 1. + */ + rb_set_parent_color(sibling, parent, + RB_RED); + if (rb_is_red(parent)) + rb_set_black(parent); + else { + node = parent; + parent = rb_parent(node); + if (parent) + continue; + } + break; } - rb_set_color(other, rb_color(parent)); - rb_set_black(parent); - rb_set_black(other->rb_right); - __rb_rotate_left(parent, root); - node = root->rb_node; - break; + /* + * Case 3 - right rotate at sibling + * (p could be either color here) + * + * (p) (p) + * / \ / \ + * N S --> N sl + * / \ \ + * sl Sr S + * \ + * Sr + * + * Note: p might be red, and then both + * p and sl are red after rotation(which + * breaks property 4). This is fixed in + * Case 4 (in __rb_rotate_set_parents() + * which set sl the color of p + * and set p RB_BLACK) + * + * (p) (sl) + * / \ / \ + * N sl --> P S + * \ / \ + * S N Sr + * \ + * Sr + */ + tmp1 = tmp2->rb_right; + WRITE_ONCE(sibling->rb_left, tmp1); + WRITE_ONCE(tmp2->rb_right, sibling); + WRITE_ONCE(parent->rb_right, tmp2); + if (tmp1) + rb_set_parent_color(tmp1, sibling, + RB_BLACK); + augment_rotate(sibling, tmp2); + tmp1 = sibling; + sibling = tmp2; } - } - else - { - other = parent->rb_left; - if (rb_is_red(other)) - { - rb_set_black(other); - rb_set_red(parent); - __rb_rotate_right(parent, root); - other = parent->rb_left; - } - if ((!other->rb_left || rb_is_black(other->rb_left)) && - (!other->rb_right || rb_is_black(other->rb_right))) - { - rb_set_red(other); - node = parent; - parent = rb_parent(node); + /* + * Case 4 - left rotate at parent + color flips + * (p and sl could be either color here. + * After rotation, p becomes black, s acquires + * p's color, and sl keeps its color) + * + * (p) (s) + * / \ / \ + * N S --> P Sr + * / \ / \ + * (sl) sr N (sl) + */ + tmp2 = sibling->rb_left; + WRITE_ONCE(parent->rb_right, tmp2); + WRITE_ONCE(sibling->rb_left, parent); + rb_set_parent_color(tmp1, sibling, RB_BLACK); + if (tmp2) + rb_set_parent(tmp2, parent); + __rb_rotate_set_parents(parent, sibling, root, + RB_BLACK); + augment_rotate(parent, sibling); + break; + } else { + sibling = parent->rb_left; + if (rb_is_red(sibling)) { + /* Case 1 - right rotate at parent */ + tmp1 = sibling->rb_right; + WRITE_ONCE(parent->rb_left, tmp1); + WRITE_ONCE(sibling->rb_right, parent); + rb_set_parent_color(tmp1, parent, RB_BLACK); + __rb_rotate_set_parents(parent, sibling, root, + RB_RED); + augment_rotate(parent, sibling); + sibling = tmp1; } - else - { - if (!other->rb_left || rb_is_black(other->rb_left)) - { - rb_set_black(other->rb_right); - rb_set_red(other); - __rb_rotate_left(other, root); - other = parent->rb_left; + tmp1 = sibling->rb_left; + if (!tmp1 || rb_is_black(tmp1)) { + tmp2 = sibling->rb_right; + if (!tmp2 || rb_is_black(tmp2)) { + /* Case 2 - sibling color flip */ + rb_set_parent_color(sibling, parent, + RB_RED); + if (rb_is_red(parent)) + rb_set_black(parent); + else { + node = parent; + parent = rb_parent(node); + if (parent) + continue; + } + break; } - rb_set_color(other, rb_color(parent)); - rb_set_black(parent); - rb_set_black(other->rb_left); - __rb_rotate_right(parent, root); - node = root->rb_node; - break; + /* Case 3 - left rotate at sibling */ + tmp1 = tmp2->rb_left; + WRITE_ONCE(sibling->rb_right, tmp1); + WRITE_ONCE(tmp2->rb_left, sibling); + WRITE_ONCE(parent->rb_left, tmp2); + if (tmp1) + rb_set_parent_color(tmp1, sibling, + RB_BLACK); + augment_rotate(sibling, tmp2); + tmp1 = sibling; + sibling = tmp2; } + /* Case 4 - right rotate at parent + color flips */ + tmp2 = sibling->rb_right; + WRITE_ONCE(parent->rb_left, tmp2); + WRITE_ONCE(sibling->rb_right, parent); + rb_set_parent_color(tmp1, sibling, RB_BLACK); + if (tmp2) + rb_set_parent(tmp2, parent); + __rb_rotate_set_parents(parent, sibling, root, + RB_BLACK); + augment_rotate(parent, sibling); + break; } } - if (node) - rb_set_black(node); } -void rb_erase(struct rb_node *node, struct rb_root *root) +/* Non-inline version for rb_erase_augmented() use */ +void __rb_erase_color(struct rb_node *parent, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)) { - struct rb_node *child, *parent; - int color; + ____rb_erase_color(parent, root, augment_rotate); +} - if (!node->rb_left) - child = node->rb_right; - else if (!node->rb_right) - child = node->rb_left; - else - { - struct rb_node *old = node, *left; +/* + * Non-augmented rbtree manipulation functions. + * + * We use dummy augmented callbacks here, and have the compiler optimize them + * out of the rb_insert_color() and rb_erase() function definitions. + */ - node = node->rb_right; - while ((left = node->rb_left) != NULL) - node = left; - - if (rb_parent(old)) { - if (rb_parent(old)->rb_left == old) - rb_parent(old)->rb_left = node; - else - rb_parent(old)->rb_right = node; - } else - root->rb_node = node; - - child = node->rb_right; - parent = rb_parent(node); - color = rb_color(node); - - if (parent == old) { - parent = node; - } else { - if (child) - rb_set_parent(child, parent); - parent->rb_left = child; +static inline void dummy_propagate(struct rb_node *node, struct rb_node *stop) {} +static inline void dummy_copy(struct rb_node *old, struct rb_node *new) {} +static inline void dummy_rotate(struct rb_node *old, struct rb_node *new) {} - node->rb_right = old->rb_right; - rb_set_parent(old->rb_right, node); - } +static const struct rb_augment_callbacks dummy_callbacks = { + .propagate = dummy_propagate, + .copy = dummy_copy, + .rotate = dummy_rotate +}; - node->rb_parent_color = old->rb_parent_color; - node->rb_left = old->rb_left; - rb_set_parent(old->rb_left, node); +void rb_insert_color(struct rb_node *node, struct rb_root *root) +{ + __rb_insert(node, root, dummy_rotate); +} - goto color; - } +void rb_erase(struct rb_node *node, struct rb_root *root) +{ + struct rb_node *rebalance; + rebalance = __rb_erase_augmented(node, root, &dummy_callbacks); + if (rebalance) + ____rb_erase_color(rebalance, root, dummy_rotate); +} - parent = rb_parent(node); - color = rb_color(node); - - if (child) - rb_set_parent(child, parent); - if (parent) - { - if (parent->rb_left == node) - parent->rb_left = child; - else - parent->rb_right = child; - } - else - root->rb_node = child; +/* + * Augmented rbtree manipulation functions. + * + * This instantiates the same __always_inline functions as in the non-augmented + * case, but this time with user-defined callbacks. + */ - color: - if (color == RB_BLACK) - __rb_erase_color(child, parent, root); +void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)) +{ + __rb_insert(node, root, augment_rotate); } /* @@ -312,24 +486,27 @@ struct rb_node *rb_next(const struct rb_node *node) { struct rb_node *parent; - if (rb_parent(node) == node) + if (RB_EMPTY_NODE(node)) return NULL; - /* If we have a right-hand child, go down and then left as far - as we can. */ + /* + * If we have a right-hand child, go down and then left as far + * as we can. + */ if (node->rb_right) { - node = node->rb_right; + node = node->rb_right; while (node->rb_left) - node=node->rb_left; + node = node->rb_left; return (struct rb_node *)node; } - /* No right-hand children. Everything down and left is - smaller than us, so any 'next' node must be in the general - direction of our parent. Go up the tree; any time the - ancestor is a right-hand child of its parent, keep going - up. First time it's a left-hand child of its parent, said - parent is our 'next' node. */ + /* + * No right-hand children. Everything down and left is smaller than us, + * so any 'next' node must be in the general direction of our parent. + * Go up the tree; any time the ancestor is a right-hand child of its + * parent, keep going up. First time it's a left-hand child of its + * parent, said parent is our 'next' node. + */ while ((parent = rb_parent(node)) && node == parent->rb_right) node = parent; @@ -340,20 +517,24 @@ struct rb_node *rb_prev(const struct rb_node *node) { struct rb_node *parent; - if (rb_parent(node) == node) + if (RB_EMPTY_NODE(node)) return NULL; - /* If we have a left-hand child, go down and then right as far - as we can. */ + /* + * If we have a left-hand child, go down and then right as far + * as we can. + */ if (node->rb_left) { - node = node->rb_left; + node = node->rb_left; while (node->rb_right) - node=node->rb_right; + node = node->rb_right; return (struct rb_node *)node; } - /* No left-hand children. Go up till we find an ancestor which - is a right-hand child of its parent */ + /* + * No left-hand children. Go up till we find an ancestor which + * is a right-hand child of its parent. + */ while ((parent = rb_parent(node)) && node == parent->rb_left) node = parent; @@ -365,20 +546,51 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new, { struct rb_node *parent = rb_parent(victim); + /* Copy the pointers/colour from the victim to the replacement */ + *new = *victim; + /* Set the surrounding nodes to point to the replacement */ - if (parent) { - if (victim == parent->rb_left) - parent->rb_left = new; - else - parent->rb_right = new; - } else { - root->rb_node = new; - } if (victim->rb_left) rb_set_parent(victim->rb_left, new); if (victim->rb_right) rb_set_parent(victim->rb_right, new); + __rb_change_child(victim, new, parent, root); +} - /* Copy the pointers/colour from the victim to the replacement */ - *new = *victim; +static struct rb_node *rb_left_deepest_node(const struct rb_node *node) +{ + for (;;) { + if (node->rb_left) + node = node->rb_left; + else if (node->rb_right) + node = node->rb_right; + else + return (struct rb_node *)node; + } +} + +struct rb_node *rb_next_postorder(const struct rb_node *node) +{ + const struct rb_node *parent; + if (!node) + return NULL; + parent = rb_parent(node); + + /* If we're sitting on node, we've already seen our children */ + if (parent && node == parent->rb_left && parent->rb_right) { + /* If we are the parent's left node, go to the parent's right + * node then all the way down to the left */ + return rb_left_deepest_node(parent->rb_right); + } else + /* Otherwise we are the parent's right node, and the parent + * should be next */ + return (struct rb_node *)parent; +} + +struct rb_node *rb_first_postorder(const struct rb_root *root) +{ + if (!root->rb_node) + return NULL; + + return rb_left_deepest_node(root->rb_node); } diff --git a/dlm_controld/rbtree.h b/dlm_controld/rbtree.h index 9a4ad60..ddb86ff 100644 --- a/dlm_controld/rbtree.h +++ b/dlm_controld/rbtree.h @@ -1,20 +1,8 @@ +/* Copied from linux/include/linux/rbtree.h */ /* Red Black Trees (C) 1999 Andrea Arcangeli - This program is free software; you can redistribute it and/or modify - it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 2 of the License, or - (at your option) any later version. - - This program is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc. linux/include/linux/rbtree.h @@ -23,138 +11,313 @@ I know it's not the cleaner way, but in C (not in C++) to get performances and genericity... - Some example of insert and search follows here. The search is a plain - normal search over an ordered tree. The insert instead must be implemented - int two steps: as first thing the code must insert the element in - order as a red leaf in the tree, then the support library function - rb_insert_color() must be called. Such function will do the - not trivial work to rebalance the rbtree if necessary. + See Documentation/core-api/rbtree.rst for documentation and samples. +*/ + +#ifndef _LINUX_RBTREE_H +#define _LINUX_RBTREE_H + +#include +#include + +#include "list.h" +#include "rbtree_types.h" + +#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3)) + +#define rb_entry(ptr, type, member) container_of(ptr, type, member) + +#define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL) + +/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */ +#define RB_EMPTY_NODE(node) \ + ((node)->__rb_parent_color == (unsigned long)(node)) +#define RB_CLEAR_NODE(node) \ + ((node)->__rb_parent_color = (unsigned long)(node)) + + +extern void rb_insert_color(struct rb_node *, struct rb_root *); +extern void rb_erase(struct rb_node *, struct rb_root *); + + +/* Find logical next and previous nodes in a tree */ +extern struct rb_node *rb_next(const struct rb_node *); +extern struct rb_node *rb_prev(const struct rb_node *); +extern struct rb_node *rb_first(const struct rb_root *); +extern struct rb_node *rb_last(const struct rb_root *); + +/* Postorder iteration - always visit the parent after its children */ +extern struct rb_node *rb_first_postorder(const struct rb_root *); +extern struct rb_node *rb_next_postorder(const struct rb_node *); + +/* Fast replacement of a single node without remove/rebalance/add/rebalance */ +extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, + struct rb_root *root); ------------------------------------------------------------------------ -static inline struct page * rb_search_page_cache(struct inode * inode, - unsigned long offset) +static inline void rb_link_node(struct rb_node *node, struct rb_node *parent, + struct rb_node **rb_link) { - struct rb_node * n = inode->i_rb_page_cache.rb_node; - struct page * page; + node->__rb_parent_color = (unsigned long)parent; + node->rb_left = node->rb_right = NULL; - while (n) - { - page = rb_entry(n, struct page, rb_page_cache); + *rb_link = node; +} - if (offset < page->offset) - n = n->rb_left; - else if (offset > page->offset) - n = n->rb_right; - else - return page; - } - return NULL; +#define rb_entry_safe(ptr, type, member) \ + ({ typeof(ptr) ____ptr = (ptr); \ + ____ptr ? rb_entry(____ptr, type, member) : NULL; \ + }) + +/** + * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of + * given type allowing the backing memory of @pos to be invalidated + * + * @pos: the 'type *' to use as a loop cursor. + * @n: another 'type *' to use as temporary storage + * @root: 'rb_root *' of the rbtree. + * @field: the name of the rb_node field within 'type'. + * + * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as + * list_for_each_entry_safe() and allows the iteration to continue independent + * of changes to @pos by the body of the loop. + * + * Note, however, that it cannot handle other modifications that re-order the + * rbtree it is iterating over. This includes calling rb_erase() on @pos, as + * rb_erase() may rebalance the tree, causing us to miss some nodes. + */ +#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \ + for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \ + pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \ + typeof(*pos), field); 1; }); \ + pos = n) + +/* Same as rb_first(), but O(1) */ +#define rb_first_cached(root) (root)->rb_leftmost + +static inline void rb_insert_color_cached(struct rb_node *node, + struct rb_root_cached *root, + bool leftmost) +{ + if (leftmost) + root->rb_leftmost = node; + rb_insert_color(node, &root->rb_root); } -static inline struct page * __rb_insert_page_cache(struct inode * inode, - unsigned long offset, - struct rb_node * node) + +static inline struct rb_node * +rb_erase_cached(struct rb_node *node, struct rb_root_cached *root) { - struct rb_node ** p = &inode->i_rb_page_cache.rb_node; - struct rb_node * parent = NULL; - struct page * page; - - while (*p) - { - parent = *p; - page = rb_entry(parent, struct page, rb_page_cache); - - if (offset < page->offset) - p = &(*p)->rb_left; - else if (offset > page->offset) - p = &(*p)->rb_right; - else - return page; - } + struct rb_node *leftmost = NULL; - rb_link_node(node, parent, p); + if (root->rb_leftmost == node) + leftmost = root->rb_leftmost = rb_next(node); - return NULL; + rb_erase(node, &root->rb_root); + + return leftmost; } -static inline struct page * rb_insert_page_cache(struct inode * inode, - unsigned long offset, - struct rb_node * node) +static inline void rb_replace_node_cached(struct rb_node *victim, + struct rb_node *new, + struct rb_root_cached *root) { - struct page * ret; - if ((ret = __rb_insert_page_cache(inode, offset, node))) - goto out; - rb_insert_color(node, &inode->i_rb_page_cache); - out: - return ret; + if (root->rb_leftmost == victim) + root->rb_leftmost = new; + rb_replace_node(victim, new, &root->rb_root); } ------------------------------------------------------------------------ -*/ -#ifndef _LINUX_RBTREE_H -#define _LINUX_RBTREE_H - -#include +/* + * The below helper functions use 2 operators with 3 different + * calling conventions. The operators are related like: + * + * comp(a->key,b) < 0 := less(a,b) + * comp(a->key,b) > 0 := less(b,a) + * comp(a->key,b) == 0 := !less(a,b) && !less(b,a) + * + * If these operators define a partial order on the elements we make no + * guarantee on which of the elements matching the key is found. See + * rb_find(). + * + * The reason for this is to allow the find() interface without requiring an + * on-stack dummy object, which might not be feasible due to object size. + */ -struct rb_node -{ - unsigned long rb_parent_color; -#define RB_RED 0 -#define RB_BLACK 1 - struct rb_node *rb_right; - struct rb_node *rb_left; -} __attribute__((aligned(sizeof(long)))); - /* The alignment might seem pointless, but allegedly CRIS needs it */ - -struct rb_root +/** + * rb_add_cached() - insert @node into the leftmost cached tree @tree + * @node: node to insert + * @tree: leftmost cached tree to insert @node into + * @less: operator defining the (partial) node order + * + * Returns @node when it is the new leftmost, or NULL. + */ +static __always_inline struct rb_node * +rb_add_cached(struct rb_node *node, struct rb_root_cached *tree, + bool (*less)(struct rb_node *, const struct rb_node *)) { - struct rb_node *rb_node; -}; + struct rb_node **link = &tree->rb_root.rb_node; + struct rb_node *parent = NULL; + bool leftmost = true; + while (*link) { + parent = *link; + if (less(node, parent)) { + link = &parent->rb_left; + } else { + link = &parent->rb_right; + leftmost = false; + } + } -#define rb_parent(r) ((struct rb_node *)((r)->rb_parent_color & ~3)) -#define rb_color(r) ((r)->rb_parent_color & 1) -#define rb_is_red(r) (!rb_color(r)) -#define rb_is_black(r) rb_color(r) -#define rb_set_red(r) do { (r)->rb_parent_color &= ~1; } while (0) -#define rb_set_black(r) do { (r)->rb_parent_color |= 1; } while (0) + rb_link_node(node, parent, link); + rb_insert_color_cached(node, tree, leftmost); -static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) -{ - rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p; + return leftmost ? node : NULL; } -static inline void rb_set_color(struct rb_node *rb, int color) + +/** + * rb_add() - insert @node into @tree + * @node: node to insert + * @tree: tree to insert @node into + * @less: operator defining the (partial) node order + */ +static __always_inline void +rb_add(struct rb_node *node, struct rb_root *tree, + bool (*less)(struct rb_node *, const struct rb_node *)) { - rb->rb_parent_color = (rb->rb_parent_color & ~1) | color; + struct rb_node **link = &tree->rb_node; + struct rb_node *parent = NULL; + + while (*link) { + parent = *link; + if (less(node, parent)) + link = &parent->rb_left; + else + link = &parent->rb_right; + } + + rb_link_node(node, parent, link); + rb_insert_color(node, tree); } -#define RB_ROOT (struct rb_root) { NULL, } -#define rb_entry(ptr, type, member) container_of(ptr, type, member) +/** + * rb_find_add() - find equivalent @node in @tree, or add @node + * @node: node to look-for / insert + * @tree: tree to search / modify + * @cmp: operator defining the node order + * + * Returns the rb_node matching @node, or NULL when no match is found and @node + * is inserted. + */ +static __always_inline struct rb_node * +rb_find_add(struct rb_node *node, struct rb_root *tree, + int (*cmp)(struct rb_node *, const struct rb_node *)) +{ + struct rb_node **link = &tree->rb_node; + struct rb_node *parent = NULL; + int c; -#define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL) -#define RB_EMPTY_NODE(node) (rb_parent(node) == node) -#define RB_CLEAR_NODE(node) (rb_set_parent(node, node)) + while (*link) { + parent = *link; + c = cmp(node, parent); -extern void rb_insert_color(struct rb_node *, struct rb_root *); -extern void rb_erase(struct rb_node *, struct rb_root *); + if (c < 0) + link = &parent->rb_left; + else if (c > 0) + link = &parent->rb_right; + else + return parent; + } -/* Find logical next and previous nodes in a tree */ -extern struct rb_node *rb_next(const struct rb_node *); -extern struct rb_node *rb_prev(const struct rb_node *); -extern struct rb_node *rb_first(const struct rb_root *); -extern struct rb_node *rb_last(const struct rb_root *); + rb_link_node(node, parent, link); + rb_insert_color(node, tree); + return NULL; +} -/* Fast replacement of a single node without remove/rebalance/add/rebalance */ -extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, - struct rb_root *root); +/** + * rb_find() - find @key in tree @tree + * @key: key to match + * @tree: tree to search + * @cmp: operator defining the node order + * + * Returns the rb_node matching @key or NULL. + */ +static __always_inline struct rb_node * +rb_find(const void *key, const struct rb_root *tree, + int (*cmp)(const void *key, const struct rb_node *)) +{ + struct rb_node *node = tree->rb_node; + + while (node) { + int c = cmp(key, node); + + if (c < 0) + node = node->rb_left; + else if (c > 0) + node = node->rb_right; + else + return node; + } + + return NULL; +} -static inline void rb_link_node(struct rb_node * node, struct rb_node * parent, - struct rb_node ** rb_link) +/** + * rb_find_first() - find the first @key in @tree + * @key: key to match + * @tree: tree to search + * @cmp: operator defining node order + * + * Returns the leftmost node matching @key, or NULL. + */ +static __always_inline struct rb_node * +rb_find_first(const void *key, const struct rb_root *tree, + int (*cmp)(const void *key, const struct rb_node *)) { - node->rb_parent_color = (unsigned long )parent; - node->rb_left = node->rb_right = NULL; + struct rb_node *node = tree->rb_node; + struct rb_node *match = NULL; - *rb_link = node; + while (node) { + int c = cmp(key, node); + + if (c <= 0) { + if (!c) + match = node; + node = node->rb_left; + } else if (c > 0) { + node = node->rb_right; + } + } + + return match; } +/** + * rb_next_match() - find the next @key in @tree + * @key: key to match + * @tree: tree to search + * @cmp: operator defining node order + * + * Returns the next node matching @key, or NULL. + */ +static __always_inline struct rb_node * +rb_next_match(const void *key, struct rb_node *node, + int (*cmp)(const void *key, const struct rb_node *)) +{ + node = rb_next(node); + if (node && cmp(key, node)) + node = NULL; + return node; +} + +/** + * rb_for_each() - iterates a subtree matching @key + * @node: iterator + * @key: key to match + * @tree: tree to search + * @cmp: operator defining node order + */ +#define rb_for_each(node, key, tree, cmp) \ + for ((node) = rb_find_first((key), (tree), (cmp)); \ + (node); (node) = rb_next_match((key), (node), (cmp))) + #endif /* _LINUX_RBTREE_H */ diff --git a/dlm_controld/rbtree_augmented.h b/dlm_controld/rbtree_augmented.h new file mode 100644 index 0000000..580a4c5 --- /dev/null +++ b/dlm_controld/rbtree_augmented.h @@ -0,0 +1,303 @@ +/* Copied from linux/include/linux/rbtree_augmented.h */ +/* + Red Black Trees + (C) 1999 Andrea Arcangeli + (C) 2002 David Woodhouse + (C) 2012 Michel Lespinasse + + + linux/include/linux/rbtree_augmented.h +*/ + +#ifndef _LINUX_RBTREE_AUGMENTED_H +#define _LINUX_RBTREE_AUGMENTED_H + +#include "rbtree.h" +#include "linux_helpers.h" + +/* + * Please note - only struct rb_augment_callbacks and the prototypes for + * rb_insert_augmented() and rb_erase_augmented() are intended to be public. + * The rest are implementation details you are not expected to depend on. + * + * See Documentation/core-api/rbtree.rst for documentation and samples. + */ + +struct rb_augment_callbacks { + void (*propagate)(struct rb_node *node, struct rb_node *stop); + void (*copy)(struct rb_node *old, struct rb_node *new); + void (*rotate)(struct rb_node *old, struct rb_node *new); +}; + +extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); + +/* + * Fixup the rbtree and update the augmented information when rebalancing. + * + * On insertion, the user must update the augmented information on the path + * leading to the inserted node, then call rb_link_node() as usual and + * rb_insert_augmented() instead of the usual rb_insert_color() call. + * If rb_insert_augmented() rebalances the rbtree, it will callback into + * a user provided function to update the augmented information on the + * affected subtrees. + */ +static inline void +rb_insert_augmented(struct rb_node *node, struct rb_root *root, + const struct rb_augment_callbacks *augment) +{ + __rb_insert_augmented(node, root, augment->rotate); +} + +static inline void +rb_insert_augmented_cached(struct rb_node *node, + struct rb_root_cached *root, bool newleft, + const struct rb_augment_callbacks *augment) +{ + if (newleft) + root->rb_leftmost = node; + rb_insert_augmented(node, &root->rb_root, augment); +} + +/* + * Template for declaring augmented rbtree callbacks (generic case) + * + * RBSTATIC: 'static' or empty + * RBNAME: name of the rb_augment_callbacks structure + * RBSTRUCT: struct type of the tree nodes + * RBFIELD: name of struct rb_node field within RBSTRUCT + * RBAUGMENTED: name of field within RBSTRUCT holding data for subtree + * RBCOMPUTE: name of function that recomputes the RBAUGMENTED data + */ + +#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \ + RBSTRUCT, RBFIELD, RBAUGMENTED, RBCOMPUTE) \ +static inline void \ +RBNAME ## _propagate(struct rb_node *rb, struct rb_node *stop) \ +{ \ + while (rb != stop) { \ + RBSTRUCT *node = rb_entry(rb, RBSTRUCT, RBFIELD); \ + if (RBCOMPUTE(node, true)) \ + break; \ + rb = rb_parent(&node->RBFIELD); \ + } \ +} \ +static inline void \ +RBNAME ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \ +{ \ + RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \ + RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \ + new->RBAUGMENTED = old->RBAUGMENTED; \ +} \ +static void \ +RBNAME ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \ +{ \ + RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \ + RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \ + new->RBAUGMENTED = old->RBAUGMENTED; \ + RBCOMPUTE(old, false); \ +} \ +RBSTATIC const struct rb_augment_callbacks RBNAME = { \ + .propagate = RBNAME ## _propagate, \ + .copy = RBNAME ## _copy, \ + .rotate = RBNAME ## _rotate \ +}; + +/* + * Template for declaring augmented rbtree callbacks, + * computing RBAUGMENTED scalar as max(RBCOMPUTE(node)) for all subtree nodes. + * + * RBSTATIC: 'static' or empty + * RBNAME: name of the rb_augment_callbacks structure + * RBSTRUCT: struct type of the tree nodes + * RBFIELD: name of struct rb_node field within RBSTRUCT + * RBTYPE: type of the RBAUGMENTED field + * RBAUGMENTED: name of RBTYPE field within RBSTRUCT holding data for subtree + * RBCOMPUTE: name of function that returns the per-node RBTYPE scalar + */ + +#define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \ + RBTYPE, RBAUGMENTED, RBCOMPUTE) \ +static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit) \ +{ \ + RBSTRUCT *child; \ + RBTYPE max = RBCOMPUTE(node); \ + if (node->RBFIELD.rb_left) { \ + child = rb_entry(node->RBFIELD.rb_left, RBSTRUCT, RBFIELD); \ + if (child->RBAUGMENTED > max) \ + max = child->RBAUGMENTED; \ + } \ + if (node->RBFIELD.rb_right) { \ + child = rb_entry(node->RBFIELD.rb_right, RBSTRUCT, RBFIELD); \ + if (child->RBAUGMENTED > max) \ + max = child->RBAUGMENTED; \ + } \ + if (exit && node->RBAUGMENTED == max) \ + return true; \ + node->RBAUGMENTED = max; \ + return false; \ +} \ +RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \ + RBSTRUCT, RBFIELD, RBAUGMENTED, RBNAME ## _compute_max) + + +#define RB_RED 0 +#define RB_BLACK 1 + +#define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) + +#define __rb_color(pc) ((pc) & 1) +#define __rb_is_black(pc) __rb_color(pc) +#define __rb_is_red(pc) (!__rb_color(pc)) +#define rb_color(rb) __rb_color((rb)->__rb_parent_color) +#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) +#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) + +static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) +{ + rb->__rb_parent_color = rb_color(rb) + (unsigned long)p; +} + +static inline void rb_set_parent_color(struct rb_node *rb, + struct rb_node *p, int color) +{ + rb->__rb_parent_color = (unsigned long)p + color; +} + +static inline void +__rb_change_child(struct rb_node *old, struct rb_node *new, + struct rb_node *parent, struct rb_root *root) +{ + if (parent) { + if (parent->rb_left == old) + WRITE_ONCE(parent->rb_left, new); + else + WRITE_ONCE(parent->rb_right, new); + } else + WRITE_ONCE(root->rb_node, new); +} + +extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); + +static __always_inline struct rb_node * +__rb_erase_augmented(struct rb_node *node, struct rb_root *root, + const struct rb_augment_callbacks *augment) +{ + struct rb_node *child = node->rb_right; + struct rb_node *tmp = node->rb_left; + struct rb_node *parent, *rebalance; + unsigned long pc; + + if (!tmp) { + /* + * Case 1: node to erase has no more than 1 child (easy!) + * + * Note that if there is one child it must be red due to 5) + * and node must be black due to 4). We adjust colors locally + * so as to bypass __rb_erase_color() later on. + */ + pc = node->__rb_parent_color; + parent = __rb_parent(pc); + __rb_change_child(node, child, parent, root); + if (child) { + child->__rb_parent_color = pc; + rebalance = NULL; + } else + rebalance = __rb_is_black(pc) ? parent : NULL; + tmp = parent; + } else if (!child) { + /* Still case 1, but this time the child is node->rb_left */ + tmp->__rb_parent_color = pc = node->__rb_parent_color; + parent = __rb_parent(pc); + __rb_change_child(node, tmp, parent, root); + rebalance = NULL; + tmp = parent; + } else { + struct rb_node *successor = child, *child2; + + tmp = child->rb_left; + if (!tmp) { + /* + * Case 2: node's successor is its right child + * + * (n) (s) + * / \ / \ + * (x) (s) -> (x) (c) + * \ + * (c) + */ + parent = successor; + child2 = successor->rb_right; + + augment->copy(node, successor); + } else { + /* + * Case 3: node's successor is leftmost under + * node's right child subtree + * + * (n) (s) + * / \ / \ + * (x) (y) -> (x) (y) + * / / + * (p) (p) + * / / + * (s) (c) + * \ + * (c) + */ + do { + parent = successor; + successor = tmp; + tmp = tmp->rb_left; + } while (tmp); + child2 = successor->rb_right; + WRITE_ONCE(parent->rb_left, child2); + WRITE_ONCE(successor->rb_right, child); + rb_set_parent(child, successor); + + augment->copy(node, successor); + augment->propagate(parent, successor); + } + + tmp = node->rb_left; + WRITE_ONCE(successor->rb_left, tmp); + rb_set_parent(tmp, successor); + + pc = node->__rb_parent_color; + tmp = __rb_parent(pc); + __rb_change_child(node, successor, tmp, root); + + if (child2) { + rb_set_parent_color(child2, parent, RB_BLACK); + rebalance = NULL; + } else { + rebalance = rb_is_black(successor) ? parent : NULL; + } + successor->__rb_parent_color = pc; + tmp = successor; + } + + augment->propagate(tmp, NULL); + return rebalance; +} + +static __always_inline void +rb_erase_augmented(struct rb_node *node, struct rb_root *root, + const struct rb_augment_callbacks *augment) +{ + struct rb_node *rebalance = __rb_erase_augmented(node, root, augment); + if (rebalance) + __rb_erase_color(rebalance, root, augment->rotate); +} + +static __always_inline void +rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root, + const struct rb_augment_callbacks *augment) +{ + if (root->rb_leftmost == node) + root->rb_leftmost = rb_next(node); + rb_erase_augmented(node, &root->rb_root, augment); +} + +#endif /* _LINUX_RBTREE_AUGMENTED_H */ diff --git a/dlm_controld/rbtree_types.h b/dlm_controld/rbtree_types.h new file mode 100644 index 0000000..d6ed904 --- /dev/null +++ b/dlm_controld/rbtree_types.h @@ -0,0 +1,34 @@ +/* Copied from linux/include/linux/rbtree_types.h */ +#ifndef _LINUX_RBTREE_TYPES_H +#define _LINUX_RBTREE_TYPES_H + +struct rb_node { + unsigned long __rb_parent_color; + struct rb_node *rb_right; + struct rb_node *rb_left; +} __attribute__((aligned(sizeof(long)))); +/* The alignment might seem pointless, but allegedly CRIS needs it */ + +struct rb_root { + struct rb_node *rb_node; +}; + +/* + * Leftmost-cached rbtrees. + * + * We do not cache the rightmost node based on footprint + * size vs number of potential users that could benefit + * from O(1) rb_last(). Just not worth it, users that want + * this feature can always implement the logic explicitly. + * Furthermore, users that want to cache both pointers may + * find it a bit asymmetric, but that's ok. + */ +struct rb_root_cached { + struct rb_root rb_root; + struct rb_node *rb_leftmost; +}; + +#define RB_ROOT (struct rb_root) { NULL, } +#define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL } + +#endif From 0ed5e3cbd812fa1e543f13076520a048adeda5f6 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Aug 21 2023 16:19:52 +0000 Subject: [PATCH 2/3] dlm_controld: update container_of() implementation This patch updates the container_of() implementation taken from the Linux kernel. We need to turn off -Wpointer-arith as the new container_of() implementation does void pointer artihmetic as shown by this example warning: linux_helpers.h:43:26: warning: pointer of type ‘void *’ used in arithmetic [-Wpointer-arith] --- diff --git a/dlm_controld/Makefile b/dlm_controld/Makefile index 28b6bb0..328a64b 100644 --- a/dlm_controld/Makefile +++ b/dlm_controld/Makefile @@ -38,7 +38,7 @@ LIB_SOURCE = lib.c CFLAGS += -D_GNU_SOURCE -O2 -ggdb \ -Wall -Wformat -Wformat-security -Wmissing-prototypes -Wnested-externs \ - -Wpointer-arith -Wextra -Wshadow -Wcast-align -Wwrite-strings \ + -Wextra -Wshadow -Wcast-align -Wwrite-strings \ -Waggregate-return -Wstrict-prototypes -Winline -Wredundant-decls \ -Wno-sign-compare -Wno-unused-parameter -Wp,-D_FORTIFY_SOURCE=2 \ -fexceptions -fasynchronous-unwind-tables -fdiagnostics-show-option \ diff --git a/dlm_controld/linux_helpers.h b/dlm_controld/linux_helpers.h index 5ef1346..09705cf 100644 --- a/dlm_controld/linux_helpers.h +++ b/dlm_controld/linux_helpers.h @@ -3,6 +3,42 @@ #ifndef __DLM_LINUX_HELPERS__ #define __DLM_LINUX_HELPERS__ +/* + * static_assert - check integer constant expression at build time + * + * static_assert() is a wrapper for the C11 _Static_assert, with a + * little macro magic to make the message optional (defaulting to the + * stringification of the tested expression). + * + * Contrary to BUILD_BUG_ON(), static_assert() can be used at global + * scope, but requires the expression to be an integer constant + * expression (i.e., it is not enough that __builtin_constant_p() is + * true for expr). + * + * Also note that BUILD_BUG_ON() fails the build if the condition is + * true, while static_assert() fails the build if the expression is + * false. + */ +#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr) +#define __static_assert(expr, msg, ...) _Static_assert(expr, msg) + +#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) + +/** + * container_of - cast a member of a structure out to the containing structure + * @ptr: the pointer to the member. + * @type: the type of the container struct this is embedded in. + * @member: the name of the member within the struct. + * + * WARNING: any const qualifier of @ptr is lost. + */ +#define container_of(ptr, type, member) ({ \ + void *__mptr = (void *)(ptr); \ + static_assert(__same_type(*(ptr), ((type *)0)->member) || \ + __same_type(*(ptr), void), \ + "pointer type mismatch in container_of()"); \ + ((type *)(__mptr - offsetof(type, member))); }) + #define WRITE_ONCE(x, val) \ do { \ *(volatile typeof(x) *)&(x) = (val); \ diff --git a/dlm_controld/list.h b/dlm_controld/list.h index a2a5e5f..e9df2ef 100644 --- a/dlm_controld/list.h +++ b/dlm_controld/list.h @@ -3,17 +3,7 @@ #ifndef _LINUX_LIST_H #define _LINUX_LIST_H -/** - * container_of - cast a member of a structure out to the containing structure - * - * @ptr: the pointer to the member. - * @type: the type of the container struct this is embedded in. - * @member: the name of the member within the struct. - * - */ -#define container_of(ptr, type, member) ({ \ - const typeof( ((type *)0)->member ) *__mptr = (ptr); \ - (type *)( (char *)__mptr - offsetof(type,member) );}) +#include "linux_helpers.h" /* * These are non-NULL pointers that will result in page faults diff --git a/dlm_controld/rbtree.h b/dlm_controld/rbtree.h index ddb86ff..48b6e32 100644 --- a/dlm_controld/rbtree.h +++ b/dlm_controld/rbtree.h @@ -20,7 +20,7 @@ #include #include -#include "list.h" +#include "linux_helpers.h" #include "rbtree_types.h" #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3)) From 8bbb1b0087d46e6d84eb80fb858e0dbe153dfa68 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Aug 21 2023 16:20:08 +0000 Subject: [PATCH 3/3] dlm_controld: update list implementation This patch updates the list implementation taken from the Linux kernel. There are new list manipulation functions introduced that could be became useful later. --- diff --git a/dlm_controld/linux_helpers.h b/dlm_controld/linux_helpers.h index 09705cf..f959cf5 100644 --- a/dlm_controld/linux_helpers.h +++ b/dlm_controld/linux_helpers.h @@ -24,6 +24,11 @@ #define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) +#define POISON_POINTER_DELTA 0xdeadbeef + +#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA) +#define LIST_POISON2 ((void *) 0x122 + POISON_POINTER_DELTA) + /** * container_of - cast a member of a structure out to the containing structure * @ptr: the pointer to the member. @@ -39,6 +44,8 @@ "pointer type mismatch in container_of()"); \ ((type *)(__mptr - offsetof(type, member))); }) +#define READ_ONCE(x) (*(const volatile typeof(x) *)&(x)) + #define WRITE_ONCE(x, val) \ do { \ *(volatile typeof(x) *)&(x) = (val); \ diff --git a/dlm_controld/list.h b/dlm_controld/list.h index e9df2ef..aab3b2b 100644 --- a/dlm_controld/list.h +++ b/dlm_controld/list.h @@ -1,20 +1,17 @@ -/* Copied from include/linux/list.h */ - +/* Copied from include/linux/list.h */ #ifndef _LINUX_LIST_H #define _LINUX_LIST_H +#include + #include "linux_helpers.h" -/* - * These are non-NULL pointers that will result in page faults - * under normal circumstances, used to verify that nobody uses - * non-initialized list entries. - */ -#define LIST_POISON1 ((void *) 0x00100100) -#define LIST_POISON2 ((void *) 0x00200200) +struct list_head { + struct list_head *next, *prev; +}; /* - * Simple doubly linked list implementation. + * Circular doubly linked list implementation. * * Some of the internal functions ("__xxx") are useful when * manipulating whole lists rather than single entries, as @@ -23,21 +20,44 @@ * using the generic single-entry routines. */ -struct list_head { - struct list_head *next, *prev; -}; - #define LIST_HEAD_INIT(name) { &(name), &(name) } #define LIST_HEAD(name) \ struct list_head name = LIST_HEAD_INIT(name) -#define INIT_LIST_HEAD(ptr) do { \ - (ptr)->next = (ptr); (ptr)->prev = (ptr); \ -} while (0) +/** + * INIT_LIST_HEAD - Initialize a list_head structure + * @list: list_head structure to be initialized. + * + * Initializes the list_head to point to itself. If it is a list header, + * the result is an empty list. + */ +static inline void INIT_LIST_HEAD(struct list_head *list) +{ + WRITE_ONCE(list->next, list); + WRITE_ONCE(list->prev, list); +} + +#ifdef CONFIG_DEBUG_LIST +extern bool __list_add_valid(struct list_head *new, + struct list_head *prev, + struct list_head *next); +extern bool __list_del_entry_valid(struct list_head *entry); +#else +static inline bool __list_add_valid(struct list_head *new, + struct list_head *prev, + struct list_head *next) +{ + return true; +} +static inline bool __list_del_entry_valid(struct list_head *entry) +{ + return true; +} +#endif /* - * Insert a new entry between two known consecutive entries. + * Insert a new entry between two known consecutive entries. * * This is only for internal list manipulation where we know * the prev/next entries already! @@ -46,10 +66,13 @@ static inline void __list_add(struct list_head *new, struct list_head *prev, struct list_head *next) { + if (!__list_add_valid(new, prev, next)) + return; + next->prev = new; new->next = next; new->prev = prev; - prev->next = new; + WRITE_ONCE(prev->next, new); } /** @@ -65,6 +88,7 @@ static inline void list_add(struct list_head *new, struct list_head *head) __list_add(new, head, head->next); } + /** * list_add_tail - add a new entry * @new: new entry to be added @@ -88,30 +112,99 @@ static inline void list_add_tail(struct list_head *new, struct list_head *head) static inline void __list_del(struct list_head * prev, struct list_head * next) { next->prev = prev; - prev->next = next; + WRITE_ONCE(prev->next, next); +} + +/* + * Delete a list entry and clear the 'prev' pointer. + * + * This is a special-purpose list clearing method used in the networking code + * for lists allocated as per-cpu, where we don't want to incur the extra + * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this + * needs to check the node 'prev' pointer instead of calling list_empty(). + */ +static inline void __list_del_clearprev(struct list_head *entry) +{ + __list_del(entry->prev, entry->next); + entry->prev = NULL; +} + +static inline void __list_del_entry(struct list_head *entry) +{ + if (!__list_del_entry_valid(entry)) + return; + + __list_del(entry->prev, entry->next); } /** * list_del - deletes entry from list. * @entry: the element to delete from the list. - * Note: list_empty on entry does not return true after this, the entry is + * Note: list_empty() on entry does not return true after this, the entry is * in an undefined state. */ static inline void list_del(struct list_head *entry) { - __list_del(entry->prev, entry->next); + __list_del_entry(entry); entry->next = LIST_POISON1; entry->prev = LIST_POISON2; } /** + * list_replace - replace old entry by new one + * @old : the element to be replaced + * @new : the new element to insert + * + * If @old was empty, it will be overwritten. + */ +static inline void list_replace(struct list_head *old, + struct list_head *new) +{ + new->next = old->next; + new->next->prev = new; + new->prev = old->prev; + new->prev->next = new; +} + +/** + * list_replace_init - replace old entry by new one and initialize the old one + * @old : the element to be replaced + * @new : the new element to insert + * + * If @old was empty, it will be overwritten. + */ +static inline void list_replace_init(struct list_head *old, + struct list_head *new) +{ + list_replace(old, new); + INIT_LIST_HEAD(old); +} + +/** + * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position + * @entry1: the location to place entry2 + * @entry2: the location to place entry1 + */ +static inline void list_swap(struct list_head *entry1, + struct list_head *entry2) +{ + struct list_head *pos = entry2->prev; + + list_del(entry2); + list_replace(entry1, entry2); + if (pos == entry1) + pos = entry2; + list_add(entry1, pos); +} + +/** * list_del_init - deletes entry from list and reinitialize it. * @entry: the element to delete from the list. */ static inline void list_del_init(struct list_head *entry) { - __list_del(entry->prev, entry->next); - INIT_LIST_HEAD(entry); + __list_del_entry(entry); + INIT_LIST_HEAD(entry); } /** @@ -121,8 +214,8 @@ static inline void list_del_init(struct list_head *entry) */ static inline void list_move(struct list_head *list, struct list_head *head) { - __list_del(list->prev, list->next); - list_add(list, head); + __list_del_entry(list); + list_add(list, head); } /** @@ -133,8 +226,61 @@ static inline void list_move(struct list_head *list, struct list_head *head) static inline void list_move_tail(struct list_head *list, struct list_head *head) { - __list_del(list->prev, list->next); - list_add_tail(list, head); + __list_del_entry(list); + list_add_tail(list, head); +} + +/** + * list_bulk_move_tail - move a subsection of a list to its tail + * @head: the head that will follow our entry + * @first: first entry to move + * @last: last entry to move, can be the same as first + * + * Move all entries between @first and including @last before @head. + * All three entries must belong to the same linked list. + */ +static inline void list_bulk_move_tail(struct list_head *head, + struct list_head *first, + struct list_head *last) +{ + first->prev->next = last->next; + last->next->prev = first->prev; + + head->prev->next = first; + first->prev = head->prev; + + last->next = head; + head->prev = last; +} + +/** + * list_is_first -- tests whether @list is the first entry in list @head + * @list: the entry to test + * @head: the head of the list + */ +static inline int list_is_first(const struct list_head *list, const struct list_head *head) +{ + return list->prev == head; +} + +/** + * list_is_last - tests whether @list is the last entry in list @head + * @list: the entry to test + * @head: the head of the list + */ +static inline int list_is_last(const struct list_head *list, const struct list_head *head) +{ + return list->next == head; +} + +/** + * list_is_head - tests whether @list is the list @head + * @list: the entry to test + * @head: the head of the list + */ +static inline int list_is_head(const struct list_head *list, const struct list_head *head) +{ + return list == head; } /** @@ -143,50 +289,155 @@ static inline void list_move_tail(struct list_head *list, */ static inline int list_empty(const struct list_head *head) { - return head->next == head; + return READ_ONCE(head->next) == head; } /** - * list_empty_careful - tests whether a list is - * empty _and_ checks that no other CPU might be - * in the process of still modifying either member - * - * NOTE: using list_empty_careful() without synchronization - * can only be safe if the only activity that can happen - * to the list entry is list_del_init(). Eg. it cannot be used - * if another CPU could re-list_add() it. + * list_rotate_left - rotate the list to the left + * @head: the head of the list + */ +static inline void list_rotate_left(struct list_head *head) +{ + struct list_head *first; + + if (!list_empty(head)) { + first = head->next; + list_move_tail(first, head); + } +} + +/** + * list_rotate_to_front() - Rotate list to specific item. + * @list: The desired new front of the list. + * @head: The head of the list. * + * Rotates list so that @list becomes the new front of the list. + */ +static inline void list_rotate_to_front(struct list_head *list, + struct list_head *head) +{ + /* + * Deletes the list head from the list denoted by @head and + * places it as the tail of @list, this effectively rotates the + * list so that @list is at the front. + */ + list_move_tail(head, list); +} + +/** + * list_is_singular - tests whether a list has just one entry. * @head: the list to test. */ -static inline int list_empty_careful(const struct list_head *head) +static inline int list_is_singular(const struct list_head *head) { - struct list_head *next = head->next; - return (next == head) && (next == head->prev); + return !list_empty(head) && (head->next == head->prev); } -static inline void __list_splice(struct list_head *list, - struct list_head *head) +static inline void __list_cut_position(struct list_head *list, + struct list_head *head, struct list_head *entry) +{ + struct list_head *new_first = entry->next; + list->next = head->next; + list->next->prev = list; + list->prev = entry; + entry->next = list; + head->next = new_first; + new_first->prev = head; +} + +/** + * list_cut_position - cut a list into two + * @list: a new list to add all removed entries + * @head: a list with entries + * @entry: an entry within head, could be the head itself + * and if so we won't cut the list + * + * This helper moves the initial part of @head, up to and + * including @entry, from @head to @list. You should + * pass on @entry an element you know is on @head. @list + * should be an empty list or a list you do not care about + * losing its data. + * + */ +static inline void list_cut_position(struct list_head *list, + struct list_head *head, struct list_head *entry) +{ + if (list_empty(head)) + return; + if (list_is_singular(head) && !list_is_head(entry, head) && (entry != head->next)) + return; + if (list_is_head(entry, head)) + INIT_LIST_HEAD(list); + else + __list_cut_position(list, head, entry); +} + +/** + * list_cut_before - cut a list into two, before given entry + * @list: a new list to add all removed entries + * @head: a list with entries + * @entry: an entry within head, could be the head itself + * + * This helper moves the initial part of @head, up to but + * excluding @entry, from @head to @list. You should pass + * in @entry an element you know is on @head. @list should + * be an empty list or a list you do not care about losing + * its data. + * If @entry == @head, all entries on @head are moved to + * @list. + */ +static inline void list_cut_before(struct list_head *list, + struct list_head *head, + struct list_head *entry) +{ + if (head->next == entry) { + INIT_LIST_HEAD(list); + return; + } + list->next = head->next; + list->next->prev = list; + list->prev = entry->prev; + list->prev->next = list; + head->next = entry; + entry->prev = head; +} + +static inline void __list_splice(const struct list_head *list, + struct list_head *prev, + struct list_head *next) { struct list_head *first = list->next; struct list_head *last = list->prev; - struct list_head *at = head->next; - first->prev = head; - head->next = first; + first->prev = prev; + prev->next = first; - last->next = at; - at->prev = last; + last->next = next; + next->prev = last; +} + +/** + * list_splice - join two lists, this is designed for stacks + * @list: the new list to add. + * @head: the place to add it in the first list. + */ +static inline void list_splice(const struct list_head *list, + struct list_head *head) +{ + if (!list_empty(list)) + __list_splice(list, head, head->next); } /** - * list_splice - join two lists + * list_splice_tail - join two lists, each list being a queue * @list: the new list to add. * @head: the place to add it in the first list. */ -static inline void list_splice(struct list_head *list, struct list_head *head) +static inline void list_splice_tail(struct list_head *list, + struct list_head *head) { if (!list_empty(list)) - __list_splice(list, head); + __list_splice(list, head->prev, head); } /** @@ -200,7 +451,24 @@ static inline void list_splice_init(struct list_head *list, struct list_head *head) { if (!list_empty(list)) { - __list_splice(list, head); + __list_splice(list, head, head->next); + INIT_LIST_HEAD(list); + } +} + +/** + * list_splice_tail_init - join two lists and reinitialise the emptied list + * @list: the new list to add. + * @head: the place to add it in the first list. + * + * Each of the lists is a queue. + * The list at @list is reinitialised + */ +static inline void list_splice_tail_init(struct list_head *list, + struct list_head *head) +{ + if (!list_empty(list)) { + __list_splice(list, head->prev, head); INIT_LIST_HEAD(list); } } @@ -209,16 +477,16 @@ static inline void list_splice_init(struct list_head *list, * list_entry - get the struct for this entry * @ptr: the &struct list_head pointer. * @type: the type of the struct this is embedded in. - * @member: the name of the list_struct within the struct. + * @member: the name of the list_head within the struct. */ #define list_entry(ptr, type, member) \ container_of(ptr, type, member) /** * list_first_entry - get the first element from a list - * @ptr: the list head to take the element from. - * @type: the type of the struct this is embedded in. - * @member: the name of the list_struct within the struct. + * @ptr: the list head to take the element from. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_head within the struct. * * Note, that list is expected to be not empty. */ @@ -226,100 +494,303 @@ static inline void list_splice_init(struct list_head *list, list_entry((ptr)->next, type, member) /** + * list_last_entry - get the last element from a list + * @ptr: the list head to take the element from. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_head within the struct. + * + * Note, that list is expected to be not empty. + */ +#define list_last_entry(ptr, type, member) \ + list_entry((ptr)->prev, type, member) + +/** + * list_first_entry_or_null - get the first element from a list + * @ptr: the list head to take the element from. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_head within the struct. + * + * Note that if the list is empty, it returns NULL. + */ +#define list_first_entry_or_null(ptr, type, member) ({ \ + struct list_head *head__ = (ptr); \ + struct list_head *pos__ = READ_ONCE(head__->next); \ + pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ +}) + +/** + * list_next_entry - get the next element in list + * @pos: the type * to cursor + * @member: the name of the list_head within the struct. + */ +#define list_next_entry(pos, member) \ + list_entry((pos)->member.next, typeof(*(pos)), member) + +/** + * list_next_entry_circular - get the next element in list + * @pos: the type * to cursor. + * @head: the list head to take the element from. + * @member: the name of the list_head within the struct. + * + * Wraparound if pos is the last element (return the first element). + * Note, that list is expected to be not empty. + */ +#define list_next_entry_circular(pos, head, member) \ + (list_is_last(&(pos)->member, head) ? \ + list_first_entry(head, typeof(*(pos)), member) : list_next_entry(pos, member)) + +/** + * list_prev_entry - get the prev element in list + * @pos: the type * to cursor + * @member: the name of the list_head within the struct. + */ +#define list_prev_entry(pos, member) \ + list_entry((pos)->member.prev, typeof(*(pos)), member) + +/** + * list_prev_entry_circular - get the prev element in list + * @pos: the type * to cursor. + * @head: the list head to take the element from. + * @member: the name of the list_head within the struct. + * + * Wraparound if pos is the first element (return the last element). + * Note, that list is expected to be not empty. + */ +#define list_prev_entry_circular(pos, head, member) \ + (list_is_first(&(pos)->member, head) ? \ + list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(pos, member)) + +/** * list_for_each - iterate over a list - * @pos: the &struct list_head to use as a loop counter. + * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list. */ #define list_for_each(pos, head) \ - for (pos = (head)->next; pos != (head); pos = pos->next) + for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next) /** - * __list_for_each - iterate over a list - * @pos: the &struct list_head to use as a loop counter. + * list_for_each_continue - continue iteration over a list + * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list. * - * This variant differs from list_for_each() in that it's the - * simplest possible list iteration code, no prefetching is done. - * Use this for code that knows the list to be very short (empty - * or 1 entry) most of the time. + * Continue to iterate over a list, continuing after the current position. */ -#define __list_for_each(pos, head) \ - for (pos = (head)->next; pos != (head); pos = pos->next) +#define list_for_each_continue(pos, head) \ + for (pos = pos->next; !list_is_head(pos, (head)); pos = pos->next) /** * list_for_each_prev - iterate over a list backwards - * @pos: the &struct list_head to use as a loop counter. + * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list. */ #define list_for_each_prev(pos, head) \ - for (pos = (head)->prev; pos != (head); pos = pos->prev) - + for (pos = (head)->prev; !list_is_head(pos, (head)); pos = pos->prev) + /** - * list_for_each_safe - iterate over a list safe against removal of list entry - * @pos: the &struct list_head to use as a loop counter. + * list_for_each_safe - iterate over a list safe against removal of list entry + * @pos: the &struct list_head to use as a loop cursor. * @n: another &struct list_head to use as temporary storage * @head: the head for your list. */ #define list_for_each_safe(pos, n, head) \ - for (pos = (head)->next, n = pos->next; pos != (head); \ - pos = n, n = pos->next) + for (pos = (head)->next, n = pos->next; \ + !list_is_head(pos, (head)); \ + pos = n, n = pos->next) + +/** + * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry + * @pos: the &struct list_head to use as a loop cursor. + * @n: another &struct list_head to use as temporary storage + * @head: the head for your list. + */ +#define list_for_each_prev_safe(pos, n, head) \ + for (pos = (head)->prev, n = pos->prev; \ + !list_is_head(pos, (head)); \ + pos = n, n = pos->prev) + +/** + * list_count_nodes - count nodes in the list + * @head: the head for your list. + */ +static inline size_t list_count_nodes(struct list_head *head) +{ + struct list_head *pos; + size_t count = 0; + + list_for_each(pos, head) + count++; + + return count; +} + +/** + * list_entry_is_head - test if the entry points to the head of the list + * @pos: the type * to cursor + * @head: the head for your list. + * @member: the name of the list_head within the struct. + */ +#define list_entry_is_head(pos, head, member) \ + (&pos->member == (head)) /** * list_for_each_entry - iterate over list of given type - * @pos: the type * to use as a loop counter. + * @pos: the type * to use as a loop cursor. * @head: the head for your list. - * @member: the name of the list_struct within the struct. + * @member: the name of the list_head within the struct. */ #define list_for_each_entry(pos, head, member) \ - for (pos = list_entry((head)->next, typeof(*pos), member); \ - &pos->member != (head); \ - pos = list_entry(pos->member.next, typeof(*pos), member)) + for (pos = list_first_entry(head, typeof(*pos), member); \ + !list_entry_is_head(pos, head, member); \ + pos = list_next_entry(pos, member)) /** * list_for_each_entry_reverse - iterate backwards over list of given type. - * @pos: the type * to use as a loop counter. + * @pos: the type * to use as a loop cursor. * @head: the head for your list. - * @member: the name of the list_struct within the struct. + * @member: the name of the list_head within the struct. */ #define list_for_each_entry_reverse(pos, head, member) \ - for (pos = list_entry((head)->prev, typeof(*pos), member); \ - &pos->member != (head); \ - pos = list_entry(pos->member.prev, typeof(*pos), member)) + for (pos = list_last_entry(head, typeof(*pos), member); \ + !list_entry_is_head(pos, head, member); \ + pos = list_prev_entry(pos, member)) /** - * list_prepare_entry - prepare a pos entry for use as a start point in - * list_for_each_entry_continue + * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue() * @pos: the type * to use as a start point * @head: the head of the list - * @member: the name of the list_struct within the struct. + * @member: the name of the list_head within the struct. + * + * Prepares a pos entry for use as a start point in list_for_each_entry_continue(). */ #define list_prepare_entry(pos, head, member) \ ((pos) ? : list_entry(head, typeof(*pos), member)) /** - * list_for_each_entry_continue - iterate over list of given type - * continuing after existing point - * @pos: the type * to use as a loop counter. + * list_for_each_entry_continue - continue iteration over list of given type + * @pos: the type * to use as a loop cursor. * @head: the head for your list. - * @member: the name of the list_struct within the struct. + * @member: the name of the list_head within the struct. + * + * Continue to iterate over list of given type, continuing after + * the current position. */ #define list_for_each_entry_continue(pos, head, member) \ - for (pos = list_entry(pos->member.next, typeof(*pos), member); \ - &pos->member != (head); \ - pos = list_entry(pos->member.next, typeof(*pos), member)) + for (pos = list_next_entry(pos, member); \ + !list_entry_is_head(pos, head, member); \ + pos = list_next_entry(pos, member)) + +/** + * list_for_each_entry_continue_reverse - iterate backwards from the given point + * @pos: the type * to use as a loop cursor. + * @head: the head for your list. + * @member: the name of the list_head within the struct. + * + * Start to iterate over list of given type backwards, continuing after + * the current position. + */ +#define list_for_each_entry_continue_reverse(pos, head, member) \ + for (pos = list_prev_entry(pos, member); \ + !list_entry_is_head(pos, head, member); \ + pos = list_prev_entry(pos, member)) + +/** + * list_for_each_entry_from - iterate over list of given type from the current point + * @pos: the type * to use as a loop cursor. + * @head: the head for your list. + * @member: the name of the list_head within the struct. + * + * Iterate over list of given type, continuing from current position. + */ +#define list_for_each_entry_from(pos, head, member) \ + for (; !list_entry_is_head(pos, head, member); \ + pos = list_next_entry(pos, member)) + +/** + * list_for_each_entry_from_reverse - iterate backwards over list of given type + * from the current point + * @pos: the type * to use as a loop cursor. + * @head: the head for your list. + * @member: the name of the list_head within the struct. + * + * Iterate backwards over list of given type, continuing from current position. + */ +#define list_for_each_entry_from_reverse(pos, head, member) \ + for (; !list_entry_is_head(pos, head, member); \ + pos = list_prev_entry(pos, member)) /** * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry - * @pos: the type * to use as a loop counter. + * @pos: the type * to use as a loop cursor. * @n: another type * to use as temporary storage * @head: the head for your list. - * @member: the name of the list_struct within the struct. + * @member: the name of the list_head within the struct. */ #define list_for_each_entry_safe(pos, n, head, member) \ - for (pos = list_entry((head)->next, typeof(*pos), member), \ - n = list_entry(pos->member.next, typeof(*pos), member); \ - &pos->member != (head); \ - pos = n, n = list_entry(n->member.next, typeof(*n), member)) + for (pos = list_first_entry(head, typeof(*pos), member), \ + n = list_next_entry(pos, member); \ + !list_entry_is_head(pos, head, member); \ + pos = n, n = list_next_entry(n, member)) + +/** + * list_for_each_entry_safe_continue - continue list iteration safe against removal + * @pos: the type * to use as a loop cursor. + * @n: another type * to use as temporary storage + * @head: the head for your list. + * @member: the name of the list_head within the struct. + * + * Iterate over list of given type, continuing after current point, + * safe against removal of list entry. + */ +#define list_for_each_entry_safe_continue(pos, n, head, member) \ + for (pos = list_next_entry(pos, member), \ + n = list_next_entry(pos, member); \ + !list_entry_is_head(pos, head, member); \ + pos = n, n = list_next_entry(n, member)) +/** + * list_for_each_entry_safe_from - iterate over list from current point safe against removal + * @pos: the type * to use as a loop cursor. + * @n: another type * to use as temporary storage + * @head: the head for your list. + * @member: the name of the list_head within the struct. + * + * Iterate over list of given type from current point, safe against + * removal of list entry. + */ +#define list_for_each_entry_safe_from(pos, n, head, member) \ + for (n = list_next_entry(pos, member); \ + !list_entry_is_head(pos, head, member); \ + pos = n, n = list_next_entry(n, member)) + +/** + * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal + * @pos: the type * to use as a loop cursor. + * @n: another type * to use as temporary storage + * @head: the head for your list. + * @member: the name of the list_head within the struct. + * + * Iterate backwards over list of given type, safe against removal + * of list entry. + */ +#define list_for_each_entry_safe_reverse(pos, n, head, member) \ + for (pos = list_last_entry(head, typeof(*pos), member), \ + n = list_prev_entry(pos, member); \ + !list_entry_is_head(pos, head, member); \ + pos = n, n = list_prev_entry(n, member)) + +/** + * list_safe_reset_next - reset a stale list_for_each_entry_safe loop + * @pos: the loop cursor used in the list_for_each_entry_safe loop + * @n: temporary storage used in list_for_each_entry_safe + * @member: the name of the list_head within the struct. + * + * list_safe_reset_next is not safe to use in general if the list may be + * modified concurrently (eg. the lock is dropped in the loop body). An + * exception to this is if the cursor element (pos) is pinned in the list, + * and list_safe_reset_next is called after re-taking the lock and before + * completing the current iteration of the loop body. + */ +#define list_safe_reset_next(pos, n, member) \ + n = list_next_entry(pos, member) #endif